Pipe joint



Oct. 4, 1949. c. w. NicHoLs PIPE JOINT Filed March 2', 1946 ATTORN EYSPatented Oct. 4, 1949 PIPE JOINT Charles W. Nichols, West Orange, N. Jassignor, by mesnc assignments, to Charles-W. Nichols,

J r., New York, N. Y.

Application March 2, 1946, Serial No. 651,537

6 Claims.

This invention relates to roasting furnaces and more particularly to theconstruction of rotatable hollow shafts used in such furnaces.

In furnaces of this type, it is customary to provide a rotatable hollowshaft having hollow rabble arms attached radially thereto. The shaft hasan inner passage through which cooling air is circulated to innerpassages in the rabble arms, returning through outer passages in therabble arms to an outer passage of the shaft. Shafts as used heretoforein such constructions have been made in sections, each of whichcomprised a single casting including integrally the inner and outertubular members of the shaft, these members being usually united througha plurality of integral webs. That integral construction has variousdisadvantages as will be pointed out more fully hereinafter. Inaccordance with the present invention, however, a construction isprovided having a hollow rotatable shaft which has separate inner andouter tubular members, which if desired may be formed of dissimilarmetals.

Various other objects, features and advantages of my invention will beapparent from a reading of the following detailed description inconnection with the accompanying drawing, in which:

Figure 1 is a sectional front elevation of a typical portion of aroasting furnace of a type in which my invention may be used, thesection being taken substantially along the vertical axis;

Fig. 2 is. an enlarged view, partly in section, of a shaft portionembodying my invention;

Fig. 3 is a horizontal sectional view of the shaft of Fig. 2; and

Fig. 4 is a vertical sectional view of an alternative form ofconstruction.

In the furnace as shown in Fig. 1 a plurality of vertically spaced andsubstantially circular hearths are provided as at III, II and I2. Thesehearths are surrounded and supported in the conventional manner by asubstantially cylindrical furnace wall l3. A rotatable shaft I4 ismounted vertically at the center of the hearths. To the shaft areattached a plurality of rabble arms l5.

having attached thereto teeth l6 so mounted as gradually to move thecharge along as the rabble arms slowly rotate.

The charge to be roasted is introduced into the furnace at its top,passingsuccessively downwardunder the impetus of gravity and the pushingof 2 the teeth IS on the rabble arms, through central opening ii tohearth H, thence through peripheral openings 8 to hearth I2 and outcentral opening |9 to discharge or to similar lower hearths.

The structure and operation thus far described above are old in the art,being shown, for example, in the patent to Dudley Baird No. 1,669,925,issued May 15, 1928.

It has been found in practical operation that under the high temperatureconditions of these furnaces the central shafts sometimes becomefractured. The furnac space about the outer periphery of the shaftreaches high temperatures and the outer part of the shaft expands. Theinner part of the shaft, on the other hand, is cooled more than theouter part by the circulating air and does not reach as hightemperatures as does the outer part, therefore does not expand to thesame extent. The result of this differential in amount of expansion isto put the integral connecting ribs under stress, sometimes to such anextent as to cause a fracture of the metal in the ribs. Replacement ofthe shafts in prior constructions has entailed considerableinconvenience and loss due to shutting down of the furnace and due tothe fact that whole shaft sections might have to be replaced, an item ofsubstantial cost, whenever a rib becomes fractured.

Moreover, shafts of integral construction as previously made aredifficult to cast, requiring intricate and expensive patterns.

Turning now to the novel features of my invention, an inspection of Fig.2 will show that I have constructed the shaft M of separate parts, outertubular sections as at '20 and 20a, inner tubular sections as at 2| and2| (1, and a keyed, supporting ring-shaped connective member 22. Thelatter member looks members 2| and 2|a so that they can not rotate withrespect to each other, such locking being accomplished by means ofcooperating lugs and notches 23 on member 22'and at the end edges oftubular members 2| and 2|a. Member 22 also has shoulders 24 extendingupwardly and downwardly on the outside of tubular members 2| and Zla.Shoulders 24 hold members 2| and 2 la in coaxial relationship. Thering-shaped member 22 is supported in the outer tubular member 20a andis locked to prevent rotation relative thereto by means of keys or lugs25 preferably located substantially symmetrically about thecircumference of member 22, and integral therewith, and cooperating withsimilarly spaced notches 2B in outer tubular section 20a. The outertubular sections 20 and 20a may be united circumferentially alongflanges 21 and 21a by means of bolts 28. It will be noted that the loweredge of section 20 overlies lugs 25, thus retaining the ring member 22securely in position.

Air for the purpose of cooling the rabble arms and shaft is introducedinto the shaft through central tubular members 2|, 2 la, etc. to thecentral tubes of rabble arms l secured in sockets, as at 29, in a mannershown in the Baird patent referred to above. The air passes through thecentral tubes of the rabble arms and back through the outer tubes ofsaid arms to cool them, then passes into the annular space between outertubular sections 20 and 20a and inner tubular sections 2| and 21a, therabble arms being secured to the outer tubular sections at sockets 30.

In Fig. 4 may be seen a modification of the structure made according tomy invention in which the ring-shaped member 3! replaces member, 22.Member 31 has formed integrally therewith keys or lugs 32 spacedpreferably substantially symmetrically'about its circumference andcooperating with grooves 33 in the outer tubular sections 291and 20a.The keys 32 are approximately triangular in form, as shown in Fig. 4and, as indicated above, are assembled in locking and supportingrelationship not only with both inner tubular sections 2! and 2 la, butalso with both outer tubular sections 28 and 28a. In other respects ringmember 31 performs the same function in the same way as does ring member22.

It will be seen that I have provided a simple, reliable constructionfora hollow rotatable shaft foruse in a roasting furnace, which is moreeconomical in upkeep than prior devices. In the first place, differencesin the rate of heating between inner and outer parts of the shaft do notput its parts in under stress as the parts are separate rather thanintegral. Thus, the tendency of such parts to fracture as a result ofstrains due to uneven rates of heating is minimized. In the secondplace, if such a part should become fractured, it can be replaced withconsiderably less delay and expense because each unit is simple inconstruction and can readily be added to or removed from the assembledstructure. Replacement of one part can be done without requiringreplacement of the whole assembly, as in prior devices. In the thirdplace,

hollow shafts of the unitary, integral inner and outer wall structureheretofore used require expensive, intricate patterns and are verydifficult to cast without causing flaws. Such patterns as are requiredfor the parts of my assembled shaftare of much simpler construction andsatisfactory casting of such designs is easier.

An additional advantage of my invention is that it makes possible theuse of different metals and alloys for parts which are in use exposed todifferent temperatures. For example, it is possible to construct theouter part of the shaft, which is exposed to higher temperatures, of analloy which will withstand such temperatures. At the same time, theinner parts of the shaft, which are cooled more by the circulating airand hence do notreach such temperatures, may beformed of a lessexpensive metal, for example 4 cast iron, which need not be able towithstand a high temperature.

What is claimed as new and desired to be secured by Letters Patent .ofthe United States, is:

1. In a roasting furnace, a rotatable hollow shaft comprising successiveinner tubular sections, successive outer tubular sections, and rings forsupporting said inner tubular sections in non-rotatable and coaxialrelationship to each other and to said outer tubular sections, each ringcomprising a member for embracing adjacent ends of two inner tubularsections and being formed with portions for keying engagement with saidouter tubular sections.

2. In a rotatable hollow shaft for a roasting furnace, the combinationof inner tubular sections, outer tubular sections, and means forsupporting and locking said inner tubular members in non-rotatable andcoaxial relationship to each other and to said outer tubular sections.

3. A device for securing together successive tubular sections of aninner rotatable shaft and for securing same in position with respect toan outer surrounding hollow rabble supporting shaft of a furnace,comprising a ring-like member adapted to embrace adjacent ends of twoinner shaft sections, the inside of said ring-like member being formedwith portions adapted to have lug and notch locking engagement with saidsection ends to prevent relative rotation thereof,

and the outer surface of said ring-like member being formed with aplurality of protruding integrally formed lugs adapted for keyingengagement with the outer shaft. p

4. A combination of parts for use in a furnace of a type having rabblearms carried by a central shaft, comprising an inner shaft formed oftubular sections, the adjacent ends of two succeeding sections beingformed with cut-out portions, a ring-like member for embracing said endsand formed with portions adapted to engage said cutout portions toprevent relative rotation of said shaft sections, an outer surroundingshaft formed of tubular sections having their inner wall surfaces spacedfrom the inner shaft sections, and means for detachably securing twosuccessive sections of the outer shaft together, said ringlike memberbeing formed with spaced lugs protruding therefrom, the inner wallsurface of the outer shaft at the line of juncture of successivesections being formed with cavities in which the outer ends of said lugsare removably received, whereby said ring-like member acts to preventrelative rotation of the inner and outer shaft sections and serves toposition the inner sections in predetermined spaced relation to theinside walls of the outer sections.

5. A device for holding in coaxial relatively non-rotatable relationshipan inner rotatable tubular section and a surrounding hollow outertubular section, comprising a pair of ring-like members each embracingan end of said inner section, the outer surface of each of said ringlikemembers having a plurality of fingers for 1 keying engagement with saidouter section, the inner surface of each of said members being formedwith portions adapted for longitudinally slidable lug and notchengagement with said inher section to prevent relative rotation thereofand to permit a lengthening of the outer shaft relative to the innershaft.

6. A device for holding in coaxial relatively non-rotatable relationshipsuccessive tubular sections of an inner rotatable shaft and for securingsame in position with respect to an outer surrounding rotatable hollowshaft of a furnace, REFERENCES CITED comprising a ring-like memberadapted to embrace adjacent ends of two inner shaft sections, g s aggggf s are of record m the the outer surface of said ring-like memberhaving a plurality of protruding fingers for keying 5 UNITED STATESPATENTS engagement with said outer shaft, the inside of Number Name Datesaid ring-like member being formed with por- 819 936 Ellis May 8 1906tions adapted for keying engagement with said n two inner sections toprevent relative rotation thereof but to permit a lengthening of saidouter 10 shaft relative to said inner shaft.

CHARLES W. NICHOLS.

